Since the Harry Potter books and films all have such long titles, I figured I was allowed one for a rough, entirely incomplete and biased retrospective of a decade (more or less) of Harry Potter films and their music. The eight films have had four composers along the way, but I (rightly or wrongly) find myself grouping them in pairs and so I'll deal with them two at a time. I'm in the process of re-watching all of the films and so it'll probably take a bit of time to complete the entire retrospective but I'm sure it'll be mildly interesting to one person. At least.
I suspect few people will need persuasion to consider the first two films and their scores together. Both films were directed by Christ Columbus and scored by John Williams. As a result of their prior working relationship (Home Alone, erm, Home Alone 2 and Stepmom), one must imagine that Williams was Columbus' first choice. I think at that point in his career, no fan of the composer expected him to launch another musical franchise. Notwithstanding the Star Wars prequels which were a continuation (of sorts) of a franchise, not many of Williams' late 90's scores had themes that hit home in the way his late 70's to early 90's output did. Harry Potter changed that run and Hedwig's theme - the first few notes are enough for even the casual cinema goer's recognition - became the defining musical accompaniment to JK Rowling's world.
One comment I have made on a couple of occasions, most notably in my review of Harry Gregson-Williams' score to The Lion, the Witch and the Wardrobe, is how easy it is to take someone of John Williams' talent for granted. Oddly named it might be, but Hedwig's Theme catches the ear instantly. Gregson-Williams can be a fine enough composer, but even a handful of plays of his Narnia score (and its first sequel) and I can barely remember any of the main themes. Williams' Potter music is, like so many of his classics, instantly memorable and not just to film score geeks.
Both scores are filled to the brim with other memorable melodies, but the tone is generally grandiose and there is little room for subtlety, but the insistence of the music gives both films much of their atmosphere. Almost every bit of Hogwarts seems to get its own theme - grand for the great hall, more gothic and scary for the outside - in a way that Williams has rarely done since the mid/late 90's. When it comes to taking composers for granted, it's too easy to forget that many of the B themes in Williams scores are better than a lot of composer's best material. True, after a while you can have heard a couple of the major themes one to many times and the dialled down use in later instalments was probably a wise move, but the series couldn't have started on a stronger musical footing.